| 摘要 |
<p>A coupler (10) suitable for connection of a transceiver to a local-area network (LAN) the nodes of which are interconnected by single unshielded twisted-pair wires (12). The coupler is constructed of inexpensive components yet supports communication rates of ten million bits per second. The coupler avoids "collisions" which would otherwise occur when using single 2-wire pairs. A transmit-sensing portion (52) of the coupler detects operation of the transmitter portion of the transceiver and forces a pair of transistors (32,34) to a state in which one transistor is conducting and the other is non-conducting. A resistor (22) connected to the non-conducting transistor develops a signal across its terminals approximately equal to zero voltage. The signal across the resistor is applied to the inverting and non-inverting inputs of an operational amplifier (62) which generates a signal conducted to the receiver portion of the transceiver. In this way, during transmission the coupler assures that no signal will be received by the transceiver. The transmit-sensing portion (52) will also detect disablement of the transmitter portion, and will cause the formerly non-conducting transistor to become saturated; in turn causing the signal across the resistor terminals to equal any signal received over the network from another transmitter. This signal will be applied to the operational amplifier, and in turn, to the receiver portion of the transceiver.</p> |
